New features and testing

Add new features and improve testing and coverage

v2.0.0

Major update of the Python API:

• Split API to ease extensions and debugging
• Add TTI SSA wave equation
• Checkpointing/on-the-fly Fourier now enabled for most cases (extended source, ...)

JUDI:

• Interface to devito now its separate file
• Supports TTI (in theory for all examples/cases)

Final JUDI version w/o TTI for legacy purposes

v1.2.5

remove obsolete versions